Hand-propelled polishing machine



Jan. 10, 1961 J. D. HELBIG E.TAL 2,967,315

HAND-PROPELLED POLISHING MACHINE Filed Jan. 28, 1957' 2 Sheets-Sheet 1 lf l H 1 I 1 J I v 33 l 22 22 I I u ii I H Q/ .4 I 5 mm 3/: 1

I I I I 1 3 37 I, ii

INVENTORS 1: I q- 2 Jim 0. Helbig Marvin ,P. Warner BY wmw ww ATTORNEYSJan. 10, 1961 J. D. HELBIG ETAL ,315

HAND-PROPELLED POLISHING MACHINE Filed Jan. 28, 1957 2 Sheets-Sheet 2INVENTOBS I I q-6 Jim 0. He/big Marvin P. Warner ATTQRNEYS United StatesPatent HAND-PROPELLED POLISHING MACHINE Jim D. Helbig, Wheatridge, andMarvin P. Warner, Denver, Colo., assignors, by mesne assignments, toJerome D. Rosenberg, Newark, NJ.

Filed Jan. 28, 1957, Ser. No. 636,684

6 Claims. (Cl. 15-49) This invention relates to polishing machines orabrading apparatus and particularly to an improved handpropelled floorpolishing machine of the single head type.

Various forms of floor polishing machines have been provided heretoforewhich have single rotary or oscillatory heads. When single head machineshave been designed for manipulation by hand, and particularly for homeuse, difficulties have been encountered because of vibration and alsobecause of the tendency of the machine to travel or drive itself overthe floor and render it difficult for the operator toguide and controlits course. The single-head machines have the advantage of simpliclty orconstruction over that employed in the multiplehead machines, and,accordingly, it is an object of the present invention to provide asingle-head hand-propelled POllSl'llIlg machine including an improvedarrangement for securing ease of handling and freedom from vibration.

it is another object of this invention to provide an improvedfloor-polishing machine of the single-head oscillatory type.

Further objects and advantages of this invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize the invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

Briefly, in carrying out the objects of this invention in one embodimentthereof, a hand-manipulated floorpolishing machine is provided with asingle head which is freely rotatable upon a short arm eccentricallydriven directly by the motor of the polisher. The head is formed toprovide a hollow or cup surrounding theend of the drive shaft and theeccentric mounting, and a counterweight for balancing the eccentricityis mounted within the hollow so that both the head and the counterweighthave their centers of gravity in substantially the same plane normal tothe axis of rotation of the shaft. A second counterweight is providedspaced ninety degrees from the common axis of the first counterweightand the eccentric and is made of size such that it effectively balancesout the reactive force which occurs upon engagement of the head with thesurface to be polished during operation. In addition to these features,the manipulating handle is secured to the body of the polisher byresilient connections which lie substantially in the plane of the centerof gravity of the unit normal to the axis of rotation of the motor, and,when a brushis employed, the bristles are mounted so that all slope inthe same direction substantially tangential to the brush circle. Thiscombination of features provides a polishing machine which is remarkablyfree of vibration and is extremely easy to manipulate over the surfaceto be polished.-

For a better understanding of this invention, reference may be had totheaccompinying drawings, in which:

Fig. 1 is an elevation view of a hand-manipulated floor-polishingmachine embodying the invention;

Fig.2 is an enlarged front sectional elevation view of the motor andhead assembly;

ice

Fig. 3 is a partial sectional view along the line 3-3 of Fig. 2;

Fig. 4 is a rear elevation view along the line designated 44 in Fig. 3;

Fig. 5 is a bottom view of the polishing head; and

Fig. 6 is a diagram illustrating the operating characteristics of thecounterweights.

Referring now to the drawings, the polishing machine illustrated in Fig.1 comprises a body portion 10 including a casing 11 having a rubberbumper guard 12 and a freely rotatable polishing brush or head 13extending below the casing 11 for engagement with the floor or othersurface to be polished. The machine is manipulated by a handle 14 havinga grip 15 and arranged to be connected to a suitable source ofelectrical power through a cord 16 extending from the end of the handle.The handle 14 is secured to the machine by a yoke or bifurcated member17 which is pivotally mounted on the mechanisms so that the handle 14may be raised and lowered through a predetermined arc.

The details of construction of the machine are shown in Figs. 2 through5. The driving motor of the machine, indicated at 19, is surrounded bythe casing 11 and the casing is attached to it by bolts 20 which passthrough the motor housing and engage the casing at the top thereof. Thetwo arms of the yoke 17 are attached to the motor on extension members21 by bolts 22 suspended in rubber grommets 23 mounted in holes inupturned ends 24 of the members 21. The bolts 22 are securely attachedto the lower ends of the yoke arms 17 and the rubber grommets 23 providea resilient connection between the handle and the machine. When the yoke17 is pivoted about its lower ends, it moves in slots 25 provided in thecasing 11 for this purpose. The polishing head 13 comprises a ring ofbristles 26 secured in a rim or annulus 27 which is snapped intoposition on an inclined flange 29 of a disc or wheel 30. The wheel 30 isprovided with a ball-bearing hub mounted on a pivot pin 31 secured to aplate 32 mounted at the lower end of the shaft 33 of the motor 19 forrotation therewith. The pivot 31 is eccentric with respect to the motorshaft 33, and the polishing head is freely rotatable about the pivot.Thus, as the motor rotates, all portions of the polishing head describesmall circles and the head is operated with an oscillating motion whichmay be described as non-linear translatory movement.

in order to counterbalance tne eccentric rotating mass of the polishinghead, the mounting member 32 is provided with a counterweight 35 whichis shown in Fig. 3 as semicircular in form, extending from a part otfsetfrom the portion to which the shaft 33 is secured, diametricallyopposite the crank arm or axis of the pivot 31. The counterweight 35operates within the hollow formed by the flange 29 of the disc 36. inorder to minimize the torque couples which might otherwise exist aboutaxes normal to the axis of the motor 33, both the counterweight and thepolishing head assembly including the disc 3t) and the attached head 13are arranged so that their centers of gravity lie in substantially thesame plane normal to the axis of the motor 33; this plane lies withinthe hollow portion of the head about the pivot end 31. For ease inattaching and detaching the ring 26, the disc 3th is provided with aplurality of spring-pressed ball motor 19 is energized to rotate theshaft 33 at a high speed, and, when the brush 13 is out of engagementwith the surface to be polished, the forces due to rotation of theeccentric head are substantially balanced out, the counterweight 35 andhead 13 being of substantially equal moment and rotating opposite eachother about the shaft 33. The arrangement of the counterweight 35 withinthe hub of the head so that the centers of gravity of the head of thecounterweight are in substantially the same plane minimizes the torquecouples about axes normal to the shaft 33 and further serves to minimizevibrations set up by operation of the machine.

When the head 13 is in engagement with the floor or other surface to bepolished, reaction forces occur between the fioor and the brush whichforces are transmitted to the machine and are exerted against themachine to produce unbalanced conditions and vibration. In order tominimize the vibrations caused by these reaction forces and therebydecrease the total vibration present in the machine during the polishingoperation a second or auxiliary counterweight, indicated at 40, isprovided; the auxiliary weight in the embodiment illustrated comprisesan upward extension 40a and a continuation 4912 both cast as portions ofthe weight 35 and extends generally along an axis at ninety degrees tothe symmetrical axis of the main portion of the weight 35 through itspivot on the shaft 33. The shaft 33, during operation, is rotated in aclockwise direction as viewed from the top in Fig. 3. It will thus beseen that, when the brush 13 is in engagement with the floor below themachine, the reactive forces caused by this engagement will be exerteddownwardly against the shaft 31 as viewed in Fig. 3, the shaft movinginstantaneously upwardly as viewed in this figure. The instantaneousforce on the weight 40 is upwardly away from the shaft 33 and is thusopposite to the instantaneous reactive force occurring upon engagementof the brush with the floor. By selecting the size of the weight 40 tocounterbalance the average force resulting from the reaction of themachine on the floor, this reaction may be substantially balanced outwhile the head is in engagement with the floor. The completecounterweight system thus provides a resultant force vector comprising amain component directly opposite and equal to that of the eccentricassembly and a small lateral component at ninety degrees leading theeccentric axis in the direction of rotation of the shaft. The resultantvector thus leads the eccentric axis by somewhat less than one hundredeighty degrees. Thus, when the head is lifted from the floor thecounterweight system is unbalanced due to the weight 40 which producesvibration in an otherwise balanced system; this latter vibration is notobjectionable, however, since it exists only during rare occasions whenthe machine is lifted from the floor and the motor operated. The effectof the auxiliary counterweight is thus to balance out forces whichotherwise would be unbalanced and produce additional vibration duringthe operation of the machine in engagement with the work. The effect ofany vibration which may exist due to varying conditions during theoperation of the machine is minimized by the resilient mounting of theyoke 17 on the machine by means of the soft rubber gaskets or grommets23 which reduce the vibration transmitted to the operators hand.

The balancing out of the several forces existing due to the rotation ofthe equipment when in engagement with the floor is indicated in thediagram, Fig. 6, which shows the counterweights 35 and 40 with vectorsrepresenting the magnitude and direction of the forces. The rotation ofthe shaft 33 is clockwise as indicated by an arrow 41. The outward forceof the counterweight 35 is represented by a vector 42 and that of thehead by an equal vector 43. The reactive force resulting from engagementof the head with the floor is represented by a vector 44 and thebalancing force of the counterweight 40 by a vector 45.

The machine, when employed with a brush, as in the illustratedembodiment, operates more smoothly when the bristles of the brush areall sloped in one direction as shown and extend outwardly-and alsobackwardly with respect to the direction of rotation of the motor shaft.It will readily be understood, however, that the polishing machine isnot limited to operation with brush or bristle heads but may employ anyof the usual types of polishing or abrading heads now available.

Various modifications and other applications of the invention will beapparent to those skilled in the art, therefore, it is not desired thatthe invention be limited to the particular construction illustrated anddescribed, and it is intended by theappended claims to cover allmodifications which fall within the spirit and scope of the invention.

We claim:

1. A hand-propelled floor polisher or the like comprising a polishinghead, a motor for said polisher having a shaft projecting therefrom,means including a bearing and a detachable pin for pivotally mountingsaid head eccentrically of said shaftand affording free rotation of saidhead about its pivotal axis, said head having a hollow portion thereinopening upwardly and extending about its pivotal axis, the center ofgravity of the head lying in a plane normal to the pivotal axis of thehead and extending through the hollow portion of the head, said mountingmeans including a plate secured to the motor shaft, which plate includesan offset portion lying within said hollow portion of said headlaterally of said bearing, and a counterweight secured to said offsetportion on the side of said mounting means opposite said pivotal axisand with its center of gravity substantially in said plane within thehollow portion of said head whereby said counterweight and said headrotate with their centers of gravity substantially in the same plane forbalancing the rotating portions of said head with minimum force couplesabout axes transverse to the axis of rotation of said shaft.

2. A hand-propelled floor polisher or the like asset forth in claim 1including a handle resiliently secured to said motor at points lyingsubstantially in a plane perpendicular to the axis of rotation of saidshaft and passing through the center of gravity of said polisher.

3. A hand-propelled floor polisher or the like comprising a motor havinga rotary shaft, 21 work head, means for mounting said head on said shaftfor free rotation about an eccentric axis parallel to that of saidshaft, and a counterweight on said shaft for balancing the moment ofsaid head about said shaft and for substantially overcoming the reactiveforce against said shaft occurring upon engagement of said head and aworksurface, the center of gravity of said counterweight lying radiallyof said shaft in a position with respect to the direction of rotation ofsaid shaft which leads the eccentric axis less than one hundred eightydegrees whereby the resultant force on said shaft comprises a firstcomponent directly opposite the force produced by rotation of said headabout the shaft and a second component leading said eccentric axis byninety degrees in the direction of rotation of said shaft for opposingthe reactive force occurring upon engagement of the head with a worksurface.

4. A hand-propelled fioor polisher or the like comprising a motor havinga rotary shaft, a work head, means for mounting said head on said shaftfor free rotation about an eccentric axis parallel to that of saidshaft, and a counterweight system for said head comprising a firstportion, having its center of gravity in the common plane of saideccentric and shaft axes and having a moment equal and opposite to thatof said head and a second portion having a center of gravity lyinglaterally of said plane and leading said eccentric axis by substantiallyninety degrees in the direction of rotation of said shaft whereby saidsecond portion produces a force in opposition to the reactive forceagainst said shaft which occurs upon engagement of said head with a worksurface.

5. A hand-propelled poliaher or the like as set forth in claim 4 whereinsaid work head comprises a body having a hollow portion extending aroundsaid eccentric axis of the head, the center of gravity of said headlying on a plane normal to the eccentric axis of the head and extendingthrough the hollow portion of the head and where in the center ofgravity of said counterweight system lies substantially in said normalplane within said hollow portion.

6. A hand-propelled floor polisher or the like comprising a polishinghead, a motor for said polisher having a shaft projecting therefrom,means for mounting said head on said shaft for free rotation about anaxis eccentric to that of said shaft, said head having a hollow portiontherein opening upwardly and extending about its pivotal axis, thecenter of gravity of the head lying on a plane normal to the pivotalaxis of the head and extending through the hollow portion of the head,said mounting means including a plate secured to the motor shaft,

which plate includes an offset portion lying within said hollow portionof said head laterally of said bearing, and a counterweight secured tosaid offset portion on the side of said mounting means opposite saidpivotal axis and with its center of gravity substantially in said planewithin the hollow portion of the said head, whereby said counterweightand said head rotate with their centers of gravity substantially in thesame plane for balancing the rotating portions of said head with minimumforce couples about axes transverse to the axis of rotation of saidshaft.

References Cited in the file of this patent UNITED STATES PATENTS1,497,921 Levedahl June 17, 1924 1,957,790 Mavis et a1 May 8, 19342,023,588 Heckroth Dec. 10, 1935 2,545,635 Steibel May 20, 19512,727,262 Gerber Dec. 20, 1955 2,774,199 Emmons Dec. 18, 1956

